Method of making fuel injection valve

ABSTRACT

THERE IS DESCRIBED A FUEL INJECTION VALVE WHICH IS MADE IN THE FOLLOWING MANNER: TWO METALS STRIPS, ONE OF WHICH IS PROVIDED ON ONE FACE WITH PARALLEL EXTENDING LONGITUDINAL GROOVES, ARE SUPERPOSED IN REGISTRY AND WITH THE GROOVED FACE COVERED. THEREUPON THE STRIPS ARE BENT AS A UNIT TO FORM A DOUBLE-JACKETED TUBULAR BODY WHICH IS SUBSEQUENTLY WELDED AND CUT INTO REQUIRED LENGTHS. ANNULAR   INLET AND OUTLET GROOVES ARE PROVIDED IN SAID BODY TO COMMUNICATE WITH INTERNAL LONGITUDINAL FUEL CHANNELS FORMED BY SAID LONGITUDINAL GROOVES. BY MEANS OF ROLLING OPERATIONS, THE ENDS OF SAID FUEL CHANNELS ARE SEALED AND FURTHER, CIRCUMFERENTIALLY REDUCED AREAS ARE PROVIDED IN SAID VALVE BODY FOR POSITIONING VALVE COMPONENTS THEREIN.

G. STRADTMANN METHOD OP MAKING FUEL INJECTION VALVE sept. 2s, 1971 2 Sheets-Sheet 1 Filed Dec. 16, 1969 W. msu Mm ,nm N F 4 l l i i Il I 2 l 1li. s Wl/ WWIHII lH Ww lll/Mill :lill/[IL Gunther STRADTMANN has ATTORNEY Sept. 28, 1971 G. STRADTMANN 3,608,171

METHOD OF MAKING FUEL INJECTION VALVE Filed Dec. 16, 1969 2 Sheets-Sheet 2 FIG.2

[21 (-22 l/l I t( I fH// A 6 k '\\M l iNvENToR Gunther STRADTMANN hiSATTORNEY 3,608,171 Patented Sept. 28, 1971 3,608,171 METHOD OF MAKING FUEL INJECTION VALVE Gunther Shadtmann, Bamberg, Germany, assignor to Robert Bosch GmbH, Stuttgart, Germany Filed Dec. 16, 1969, Ser. No. 885,593 Claims priority, application Germany, Dec. 18, 1968, P 18 15 260.8 Int. Cl. B21k 1/20 U.S. Cl. 29-156.7R 8 Claims ABSTRACT OF THE DISCLOSURE There is described a fuel injection valve which is made in the following manner: two metal strips, one of which is provided on one face with parallel extending longitudinal grooves, are superposed in registry and with the grooved face covered. Thereupon the strips are bent as a unit to form a double-jacketed tubular body which is subsequently welded and cut into required lengths. Annular inlet and outlet grooves are provided in said body to communicate with internal longitudinal fuel channels formed by said longitudinal grooves. By means of rolling operations, the ends of said fuel channels are sealed and further, circumferentially reduced areas are provided in said valve body for positioning valve components therein.

BACKGROUND OF THE INVENTION This invention relates to a fuel injection valve having a tubular valve body formed of two coaxially arranged tubes that enclose at least one longitudinal fuel channel which is sealed at its ends and include an inlet channel and an outlet channel. The said fuel injection valve is further of the type that is terminated at one end by a nozzle body accommodating the movable valve member and containing nozzle openings for injection. From said outlet channel there extends a port disposed in the nozzle body and leading to the pressure chamber of the fuel injection valve also contained by said nozzle body. The fuel injection valve further has a coupling means that is associated with said inlet channel and serves to attach to the fuel injection valve a pressure conduit extending from the fuel injection pump.

In a known fuel injection valve of the aforenoted type (described, for example, in French Pat. No. 1,516,678), in the intermediate space of the two coaxially arranged tubes there is inserted a further tube of identical length in which there is machined a slot of appropriate length for forming a longitudinal fuel channel. These tubes are soldered together after telescoping them into one another. Thereafter, at the proper locations radial holes are drilled into the external tube to provide an inlet and an outlet passage for the longitudinal channel or channels. During assembly of the injection valve, care has to be taken that said inlet and outlet bores exactly register with the fuel ports disposed in the nozzle holder and in the nozzle body, respectively. Such an assembling operation is relatively complex and expensive.

OBJECT, SUMMARY AND ADVANTAGES OF THE INVENTION It is an object of the invention to provide an improved, simplified and more economical method of making fuel injection valves of the aforenoted type.

Briefly stated, according to the invention, the fuel injection valve is prepared as follows:

Two steel 'strips of substantially identical width are superimposed subsequent to copper plating the contacting faces and subsequent to providing at least one longitudinal groove in one of said faces. The two superimposed strips are bent as a unit into tubular form, the longitudinally adjacent free edges of which are welded together to form a seam. The tubular body so prepared is cut into pieces of predetermined length; the concentric circular terminal edges at least at one end of each piece are pinched together by rolling to seal the ends of the longitudinal grooves serving as fuel channels. Finally, the valve body is brazed.

Such a method of manufacturing tubular valve bodies (particularly the cutting of the tubular form into several pieces of determined length), has not been possible heretofore, because the longitudinal fuel channel had to be initially dimensioned according to the length of the valve body.

In a valve body according to the invention the longitudinal fuel channel will not be blocked by pinching even if the valve body is crimped to obtain reduced areas. Thus, such crimping may freely be applied to provide securing means or shoulders particularly of annular configuration for the abutment of components (such as nozzle body, spring seat disc, coupling member, etc.) disposed in or on the tubular member.

BRIEF DESCRIPTION OF THE DRAWING The invention will be better understood, as well as further objects and advantages will become more apparent from the ensuing detailed specification of two exemplary embodiments taken in conjunction with the drawing.

FIG. 1 is an axial sectional view of a first embodiment prepared according to the invention;

1FIG. 2 is a cross-sectional view of Itwo superimposed strips from which the tubular valve body is formed;

FIG. 3 is a cross-sectional view of a tubular valve body formed according to the invention; and

FIG. `4 is an axial sectional view of a second embodiment made according to the invention.

DESCRIPTION OF THE EMBODIMENTS Turning now to `FIG. l, there is shown a tubular valve body generally indicated at 1 and formed of an inner jacket 20 and an outer jacket 21. Between the two jackets there extend a plurality of longitudinal fuel channels 2 (two shown). One end of the valve body 1 is sealed by a nozzle body 3 threadedly engaging the inner jacket 20. Over the other end portion of the valve body 1 there is drawn an annularly-shaped coupling member 4 which is connected to a pressure conduit S leading from a fuel injection pump, not shown. The pressure conduit 5 communicates with all longitudinal channels 2 by means of an annular, circumferential groove 6 provided in the outer face of jacket 21 and covered by the coupling member 4.

Radially adjacent the nozzle body 3, the inner jacket 20 of the valve body 1 is provided with an annular groove 8 which registers with at least one radial port .9 of nozzle body 3 and establishes communication through said port 9 between the longitudinal channels Z on the one hand and a pressure chamber 10 of the fuel injection valve on the other hand. The pressure chamber 10 is defined by the inner wall of the hollow nozzle body 3 and by a valve needle 12 disposed therein and adapted to be axially displaced against the force of a return spring 11. The latter engages with the interposition of a spring' seat disc 13, a shoulder 14 which is created by providing an annular reduced area 14 in the valve body 1.

In order to prevent the fuel from flowing from the annular groove 8 into the inside of the valve body 1, between the radial terminal face of nozzle body 3 and a second shoulder 15' formed in the inner jacket 20' by reduced area 15, there is disposed an annular sealing element 16. The space defined by the inner wall of jacket 20 communicates with a discharge conduit (not shown) attached to the valve body 1 at its end distal from the nozzle body 3.

According to thev invention, the tubular valve body 1 is formed as hereinafter described.

Turning now to FIG. 2, two substantially equally wide steel strips and 21, each copper-coated on one side and one provided on its coated side with parallel extending longitudinal grooves 2.2, are placed on one another in registry, with their coated sides in engagement. The superimposed strips are deformed as a unit into tubular form by means of a tube drawing machine'. Thus, strip 20 becomes inner jacket 20' and strip 21 becomes outer jacket 21'. The tubular body, which in this stage is of indefinite length, has a longitudinally extending gap which is generally wedge-shaped in cross section and which is sealed by a weld 23 (FIG. 3) provided by a welding step.

Subsequent to the aforenoted steps, the tube is cut or sawed into required lengths each corresponding to the length dimension of a fuel injection valve body. Thereafter, the reduced areas 14 and 15 are provided by a rolling operation and the thread for the nozzle bod'y 3 is cut. Then, the annular grooves 6 and 8 are provided, for example, by electrolytic means. Prior or subsequent to the provision of annular grooves 6 and 8, at least that terminal portion of jackets 20 and 21 that is distal from the end eventually receiving nozzle body 3, is pressed together at 24 by a rolling operation to seal the ends of the longitudinal fuel channels 2 (formed of longitudinal grooves 22). Thereafter, the coupling part 4 is drawn on the valve body 1 into a position in which it covers groove 6. The contacting faces of jacket 21' and coupling part 4 have previously been copper-coated.

As a final step, the valve body 1 is brazed.

While in the embodiment shown in FIG. l, the nozzle body 3 is screwed into the valve body, according to the embodiment depicted in FIG. 4, the nozzle body 3 is axially introduced into a valve body 1' until the edge of its leading end face 2S abuts the shoulder 26' of a reduced area 26. Thereafter, the terminal portion 27 of the valve body 1 is crimped (for example, by means of a rolling step) over a shoulder of the nozzle body 3' and, as a result, the latter is locked into the valve body 1'. Or, instead, by means of a rolling operation, the terminal portion of the valve body 1' may be depressed into an annular groove (not shown) previously provided in the nozzle body 3. The method of forming the valve body 1 is identical to that described in connection with valve body 1.

What is claimed is:

1. A method of making the valve body of a fuel injection valve of the type including (A) two coaxial tubes forming said valve body, (B) at least one longitudinal fuel channel disposed between said tubes and sealed at its ends, (C) an inlet channel and an outlet channel communicating with said longitudinal channel, (D) a hollow nozzle body sealingly secured to one end of said valve body and (E) coupling means associated with said inlet channel and carrying a pressure conduit leading from a fuel injection pump, comprising the following steps:

(A) bending two superposed metal strips of substantially equal width into a tubular body, one strip being provided on its face turned to the other strip, with at least one longitudinal groove constituting said longitudinal fuel channel,

(B) longitudinally welding said tubular body to form a seam,

(C) severing said tubular body into tube portions of determined length and (D) circumferentially pressing together atleast one end of each tube portion to seal an end of said longitudinal channel.

2. A method as defined in claim 1, wherein contacting faces of said strips are copper-coated prior to step 3. A method as defined in claim 1, wherein said tubular portion constituting said valve body is brazed subsequent to step (D).

4. A method as defined in claim 3, wherein prior to said brazing said tubular portion is provided with reduced areas to form internal shoulders cooperating with components inside said tube portion.

5. A method as dened in claim 3, wherein prior to said brazing an annular coupling member constituting said coupling means is drawn onto said tube portion constituting said valve body.

6. A method as dened in claim S, wherein the contacting faces of said coupling member and said valve body are copper-coated prior to drawing the former on the latter.

7. A method as defined in claim 1, wherein a terminal portion of said valve body is, by rolling, depressed into a circumferentially extending groove provided in said nozzle body positioned in said valve body.

8. A method as defined in claim 1, wherein said valve body is provided electrolytically with axially spaced grooves constituting said inlet channel and said outlet channel.

References Cited UNITED STATES PATENTS Barrett 29-455X Wilson 138-111X White 29-455X Pajak et al. 29-455 US. Cl. X.R. 

